/*
 * Copyright 2007-2008 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package jsr203.sun.nio.fs;

import java.io.IOException;
import java.security.AccessController;
import java.util.ArrayList;
import jsr203.nio.file.FileStore;
import jsr203.nio.file.WatchService;
import jsr203.nio.file.attribute.BasicFileAttributeView;
import jsr203.nio.file.attribute.DosFileAttributeView;
import jsr203.nio.file.attribute.FileAttributeView;
import jsr203.nio.file.attribute.FileOwnerAttributeView;
import jsr203.nio.file.attribute.NamedAttributeView;
import jsr203.nio.file.attribute.PosixFileAttributeView;
import static jsr203.sun.nio.fs.LinuxNativeDispatcher.endmntent;
import static jsr203.sun.nio.fs.LinuxNativeDispatcher.getextmntent;
import static jsr203.sun.nio.fs.LinuxNativeDispatcher.setmntent;
import sun.security.action.GetPropertyAction;

/**
 * Linux implementation of FileSystem
 */

class LinuxFileSystem extends UnixFileSystem {
    private final int majorVersion;
    private final int minorVersion;
    private final int microVersion;

    LinuxFileSystem(UnixFileSystemProvider provider, String dir) {
        super(provider, dir);

        // assume X.Y[-Z] format
        String osversion = AccessController
            .doPrivileged(new GetPropertyAction("os.version"));
        String[] vers = osversion.split("\\.", 0);
        if (vers.length >= 2) {
            this.majorVersion = Integer.parseInt(vers[0]);
            this.minorVersion = Integer.parseInt(vers[1]);
            if (vers.length > 2) {
                String[] microVers = vers[2].split("-", 0);
                this.microVersion = (microVers.length > 0) ?
                    Integer.parseInt(microVers[0]) : 0;
            } else {
                this.microVersion = 0;
            }
        } else {
            throw new AssertionError();
        }
    }

    @Override
    public WatchService newWatchService()
        throws IOException
    {
        // inotify available since 2.6.13
        if ((majorVersion > 2) ||
            (majorVersion == 2 && minorVersion > 6) ||
            ((majorVersion == 2) && (minorVersion == 6) && (microVersion >= 13)))
        {
            return new LinuxWatchService(this);
        }

        // use polling implementation on older kernels
        return new PollingWatchService();
    }

    @Override
    @SuppressWarnings("unchecked")
    public Iterable<Class<? extends FileAttributeView>> getFileAttributeViews() {
        ArrayList list = new ArrayList();
        list.add(BasicFileAttributeView.class);
        list.add(PosixFileAttributeView.class);
        list.add(FileOwnerAttributeView.class);
        // when xattr enabled
        list.add(DosFileAttributeView.class);
        list.add(NamedAttributeView.class);
        return list;
    }

    @Override
    @SuppressWarnings("unchecked")
    public <V extends FileAttributeView> V newFileAttributeView(Class<V> view)
    {
        if (view == DosFileAttributeView.class)
            return (V) new LinuxDosFileAttributeView();
        if (view == NamedAttributeView.class)
            return (V) new LinuxNamedAttributeView();
        return super.newFileAttributeView(view);
    }

    @Override
    void copyExtendedAttributes(int ofd, int nfd) {
        LinuxNamedAttributeView.copyExtendedAttributes(ofd, nfd);
    }

    @Override
    boolean supportsSecureDirectoryStreams() {
        // openat etc. available since 2.6.16
        if ((majorVersion > 2) ||
            (majorVersion == 2 && minorVersion > 6) ||
            ((majorVersion == 2) && (minorVersion == 6) && (microVersion >= 16)))
        {
            return true;
        }
        return false;
    }

    /**
     * Returns object to iterate over entries in /etc/mtab
     */
    @Override
    Iterable<UnixMountEntry> getMountEntries() {
        ArrayList<UnixMountEntry> entries = new ArrayList<UnixMountEntry>();
        try {
            long fp = setmntent("/etc/mtab".getBytes(), "r".getBytes());
            try {
                for (;;) {
                    UnixMountEntry entry = new UnixMountEntry();
                    int res = getextmntent(fp, entry);
                    if (res < 0)
                        break;
                    entries.add(entry);
                }
            } finally {
                endmntent(fp);
            }

        } catch (UnixException x) {
            // nothing we can do
        }
        return entries;
    }

    @Override
    FileStore getFileStore(UnixPath path) throws IOException {
        return new LinuxFileStore(path);
    }

    @Override
    FileStore getFileStore(UnixMountEntry entry) {
        return new LinuxFileStore(this, entry);
    }
}
